Answer:
(a). $20,000
(b). The estimate will be lower than the actual amount.
Explanation:
We have been given that Michael saves $423 dollars a month for college.
(a). We know that 1 year equals 12 months.
4 years = 4*12 months = 48 months.
![\text{Actual amount saved}=\$423* 48](https://img.qammunity.org/2020/formulas/mathematics/middle-school/gwnzjqkbpsww6p7yvxyf9qr8u5cdrdb2wt.png)
Since we are asked to find the estimated amount of money Michael will save in 4 years, so we will estimate both quantities as:
![423\approx 400\\\\48\approx 50](https://img.qammunity.org/2020/formulas/mathematics/middle-school/m6cl2x7pwxoapd4jfbbsbegvtjqe12fz0f.png)
![\text{Actual amount saved}=\$400* 50](https://img.qammunity.org/2020/formulas/mathematics/middle-school/n7dyeuaowh28h3rv6xksyw4yk4lmkjzb2h.png)
![\text{Actual amount saved}=\$20,000](https://img.qammunity.org/2020/formulas/mathematics/middle-school/hag4agli122z977gonq01amnznctk19kb6.png)
Therefore, Michael will save approximately $20,000 in 4 years.
(b).
The estimate will be lower than the actual amount as we rounded $423 down $23 to nearest hundred that is $400 and rounded 48 up 2 to nearest ten that is 40.
Therefore, the estimate will be lower than the actual amount.